Currently, there are several methods of controlling economically important pests such as grasshoppers and locusts. These methods fall into two broad categories--chemical and biological. Chemical methods are the most commonly used and entail the use of chemical pesticides. However, chemical pesticides can pose risks to human health and cause environmental damage due to adverse effects on non-target insects and other animals. Also, chemical pesticides used for grasshopper control are non-selective and kill other, beneficial insects in sprayed areas. In short, chemical pesticides can kill pollinating insects, adversely affecting plant life or can upset insect population balances by killing predators or parasitic insects that naturally control the insects population.
Biological methods of controlling economically-important pests have become increasingly attractive as a less ecologically-destructive way of dealing with these insects. Biological methods exploit an insect's natural enemies and include using insect parasitoids, predators, and pathogens. Of the various ways to use an insect's natural enemies as biological control agents for that insect, one of the most common is mass multiplying pathogens such as bacteria or fungi and applying them to an affected area as a biopesticide. Organisms which have been under investigation as potential biopesticides include viruses, nematodes, protozoa, bacteria and fungi.
Biopesticides can be very expensive to raise and can be difficult to deliver effectively to the target insect. To date, bacteria is a commonly used form of biopesticide. For example, strains of the bacteria Bacillus thuringiensis have been used against susceptible Lepidoptera, Diptera, and Coleoptera. Fungi such as Metarhizium and Beauveria are virulent against a wide range of insects and can be economically mass produced according to methods described in the patent application entitled "A Solid Culture Substrate Including Barley" filed even date herewith, the contents of which are expressly incorporated herein. However, Prior and Greathead (FAO Plant Prot. Bull. 37:37-48 (1989)) state that "a! pathogen such as Beauveria will kill a target insect only in an unfavourable climate, such as the majority of locust outbreak areas, if it either hits the insect directly or contacts it rapidly after application and before it is inactivated by UV, high temperature, or low relative humidity!."